They are there to hunt militants who sought refuge in the rugged tribal terrain after the ousting of the Taleban in Afghanistan in late 2001.

President Pervez Musharraf has pledged to reform madrassas after many were criticised for supporting Islamic militancy.

Monday's attack took place near Khar, the main town in Bajaur.

The leader of the madrassa, radical cleric Maulana Liaqat, was among the dead.

He was a prominent member of a group of pro-Taleban tribal clerics, the BBC's Rahimullah Yusufzai in Peshawar says.

"We received confirmed intelligence reports that 70-80 militants were hiding in a madrassa used as a terrorist training facility, which was destroyed by an army strike, led by helicopters," army spokesman Maj Gen Shaukat Sultan told the Associated Press news agency.

'Saddened'

However, an eyewitness told the BBC that the madrassa school was filled with about 80 local students who had resumed studies after the Muslim Eid holidays.

At least three helicopters were reportedly involved in the attack

People at the scene told reporters that body parts were scattered in the area after the attack.

The government had already released prisoners in anticipation of a deal, possibly along the lines of an agreement signed in the neighbouring tribal region of North Waziristan, our correspondent says.

But the army says peace talks would not be allowed to serve as a cover for militant activity.

Bajaur, which borders Afghanistan's insurgency-plagued eastern province of Kunar, was the scene of a controversial US air strike in January, believed to be aimed at al-Qaeda number two Ayman al-Zawahiri.

The 13 January raid killed at least 18 people, mostly civilians.

In May, Pakistani authorities said a senior al-Qaeda figure, Abu Marwan al-Suri, had been killed in Bajaur during a clash with local police.